The present invention relates to a disk drive and its interfacing technique that ensures a realtime nature of a realtime processing and data integrity of a non-realtime processing and, further, allows both processings to be performed efficiently when the realtime and non-realtime processings are performed simultaneously.
In a realtime processing such as an AV data processing, in order to ensure a realtime nature, a disk drive must observe a predetermined time limit accurately to perform data transfer.
To this end, in ATA/ATAPI-7 (that is in the course of standardization according to ANSI standards), it is contemplated to introduce a command set that can set a command completion time limit for each stream or each command so as to ensure the realtime nature in the AV data processing that is performed in realtime.
Further, when the realtime and non-realtime processings are performed simultaneously, a control is performed so that the realtime processing command is executed with priority and, if it is expected that there is a sufficient time to be allocated for the non-realtime processing command, the non-realtime processing command is executed within such allocatable time. Such method for controlling command execution is disclosed in Japanese Patent Laid-open No. Hei 10-222310.